A battery cell in a battery module is generally adhered onto a holder. For example, a battery module introduced in Patent literature 1 integrally adheres a plurality of battery cells to a holder. This type of battery module is also called a battery pack, and is used for various purposes such as a battery for a vehicle, or the like.
In the battery module introduced in Patent literature 1, a battery retaining section forming an aperture shape is provided in the holder, and the battery cells are inserted in this battery retaining section. Further, an adhesive is injected between an inner circumferential surface of the battery retaining section of the holder and outer circumferential surface of the battery cell, and the adhesive is solidified to form an adhesive layer. However, according to a method for injecting the adhesive between the inner circumferential surface of the battery retaining section and the outer circumferential surfaces of the battery cells (so-called potting method), the injection and solidification of the adhesive takes time, and work efficiency thereof is inferior.
To improve the work efficiency, for example, a method may be assumed in which the adhesive is coated to the outer circumferential surfaces of the battery cells, and the battery cells in a state in which the adhesive has been coated are inserted into the battery retaining section.
Meanwhile, to stably retain a battery cell on a holder, it is assumed that a gap between an inner circumferential surface of a battery retaining section provided in the holder and an outer circumferential surface of the battery cell is preferably kept small. In this case, operators have to fill a narrow gap with the adhesive. However, since the adhesive has a relatively high viscosity, a friction resistance with the inner circumferential surface of the battery retaining section is relatively large, whereby a uniform coating is difficult. Due to this, it had not been easy to uniformly spread the adhesive in the narrow gap between the inner circumferential surface of the battery retaining section and the outer circumferential surface of the battery cell. Further, when the adhesive is not sufficiently spread in the gap between the inner circumferential surface of the battery retaining section and the outer circumferential surface of the battery cell, and air is caught inside an adhesive layer, there has been a possibility that an adhering area of the adhesive and its counterpart member (that is, the inner circumferential surface of the battery retaining section and/or the outer circumferential surface of the battery cell) is reduced, or strength of an adhering layer formed of the adhesive layer is reduced. Due to this, there has been a problem that the adhering strength is difficult to improve, and the battery cell cannot be stably adhered integrally to the holder.